linux-kernel - Re: [PATCH next resend 1/5] minmax: Add min_unsigned(a, b) and max

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Message-ID: <ZL/CUuIhi6qmTK5+@casper.infradead.org>
Date:   Tue, 25 Jul 2023 13:38:42 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     David Laight <David.Laight@...lab.com>
Cc:     "'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>,
        'Andy Shevchenko' <andriy.shevchenko@...ux.intel.com>,
        'Andrew Morton' <akpm@...ux-foundation.org>,
        'Christoph Hellwig' <hch@...radead.org>,
        "'Jason A. Donenfeld'" <Jason@...c4.com>
Subject: Re: [PATCH next resend 1/5] minmax: Add min_unsigned(a, b) and
 max_unsigned(a, b)

On Tue, Jul 25, 2023 at 11:48:14AM +0000, David Laight wrote:
> +#define min_unsigned(x, y)	\
> +	__careful_cmp((x) + 0u + 0ul + 0ull, (y) + 0u + 0ul + 0ull, <)

What is the point of "+ 0u + 0ul + 0ull"?  How is that any different
from "+ 0ull"?  And why force the compiler to do a 64-bit comparison
when it could do a 32-bit comparison?